Our planet has one true ocean, interconnected and interdependent. Producing over half of the world's oxygen, it is a natural wonder and a vital resource. It teems with life and plays a crucial role in climate, food supply, medicine, recreation and transport. And yet our ocean is under threat from all sides: overfishing, climate change and pollution, to name a few. This stunning book celebrates these essential ecosystems - from the crystal waters of the Caribbean to the freezing Polar regions, from the high seas to the coral reefs - and explores ways we can preserve and protect this wondrous world.